Toward the development of a label-free multiple immunosensor based on thin film transistor microelectrode arrays

A label-free immunosensor using thin film transistor microelectrode arrays (TFT-µEAs) derived from flat-panel technology has been developed for the first time. The TFT-µEAs used here incorporate a large sensing area of 15 mm × 15 mm with a 150 × 150 array of transparent indium-tin-oxide (ITO) electrodes placed at a 100 μm pixel pitch. Anti-human serum albumin (HSA) IgG was characterized to be immobilized on functionalized ITO electrodes. HSA, which is one of the indexes for liver functions, was successfully detected by recording the change of real-time current based on the change in the electric double layer capacitance before and after conjugation of HSA with anti-HSA IgG. Ionic strength and pH value of HSA solution were optimized. In 0.01 mM phosphate buffered saline with pH 6.0, linear range of HSA was determined as 0.3-300 pM. The present TFT-µEAs are applicable to a label-free multiple immunosensing by patterning antibodies on its surface.